So I had to have my 450 cylinder head pulled out as the bike was not cranking. Its a 2004 model, and its had regular oil changes as part of its service, but nothing else has been done. When the mechanic took it apart, we found that the liner was scored and needs to be replaced, as well as the piston, and the rings. Everything else is ok otherwise. I asked the mechanic what would cause the liner to score, and his response straight off the bat with no hesitation was "your timing chain is fecked"...and did not manage to give me a convincing answer as to what caused it. My only concern is when we put it back together, I dont want it to occur again. Anyone know what would cause the piston to score the liner? or put another way, how can a bad/loose timing chain affect the motor? Timing chain according to mechanic was loose The head and valves seem ok. The scoring marks The piston/con rod pin has to be replaced.